The Stirling County Study spans 40 years and draws on a database of about 4010 adults selected sequentially to represent an area in Atlantic Canada in 1952, 1970, and 1992. The longitudinal design involves repeated cross-sectional surveys combined with cohort follow-up, and the data consist in interviews carried out with subjects and their general physicians. The procedures for psychiatric diagnosis have been consistently applied, are structurally compatible with modern approaches, and were recently updated for changes in the common words used for disturbances of mood. In the final wave of data gathering, completed in 1996, portions of the Diagnostic Interview Schedule were used to facilitate comparison with other studies; the Modified Mini-Mental Status Examination was administered to older subjects so that cognitive dysfunction could be estimated; and the Structured Clinical Interview for DSM-III-R was employed for a validity assessment. The purpose of this proposal is to request funds to complete data-processing and to conduct primary analysis and reporting. Based on the 40-year perspective, reports have recently been published on time-trends in the prevalence and incidence of depression, on comparison of lay-administered and clinician- administered interviews, and on the evolution of methods for longitudinal research. Time-trends constitute the framework for future analysis, and the topics to be addressed include: prevalence and incidence of anxiety and comorbidity with depression; clinical antecedents and subsequent course of depression and anxiety, their associations with smoking; with mortality; with socioeconomic status; with changes in the role of women; with health service use; and with the perceptions of psychiatric disorders by general physicians. Three young investigators will use data from the study to study psychiatric precursors of cognitive dysfunction, statistical procedures for handling multiple-source data, and changing practices regarding psychotropic medication. The first half of the study indicated that many types of psychiatric disorders reduce the quality and quantity of life. This research concerns whether such disorders are increasing in number or changing in clinical features.